docs: def plot(self, plotname=None, **options):
          """Plot the data"""
          if 'color' in options:
              color = options['color']
          else:
              color = 'blue'
  
          if self.wavespace == "wavelength":
              xlabel = r"Wavelength ($\mu m$)"
              ylabel = r"Irradiance ($W/(m^2 \mu m$))"
              xlim = [0, 4.2]
              xwl, yir = self.wavelength, self.irradiance
          elif self.wavespace == "wavenumber":
              xlabel = "Wavenumber ($cm^{-1}$)"
              ylabel = "Irradiance ($mW/m^2 (cm^{-1})^{-1}$))"
              xlim = [0, 35000]
              xwl, yir = self.wavenumber, self.irradiance
          else:
              raise TypeError('Neither wavelengths nor wavenumbers available!')
  
          from matplotlib import pyplot as plt
          from matplotlib import rcParams
          rcParams['text.usetex'] = True
          rcParams['text.latex.unicode'] = True
  
          fig, axl = plt.subplots(figsize=(8, 4))
          plot_title = "Solar Irradiance Spectrum"
          axl.set_title(plot_title)
  
          axl.plot(xwl, yir, '-', color=color)
  
          axl.set_xlabel(xlabel)
          axl.set_ylabel(ylabel)
          axl.set_xlim(xlim)
          axl.set_ylim([0, yir.max()])
          axl.grid(True)
  
          if plotname is None:
              plt.show()
          else:
              fig.savefig(plotname)